Film applicator for liquid or semi-liquid material



y 22, 1956 P. N. GARDNER 2,746,75

FILM APPLICATOR FOR LIQUID OR SEMI-LIQUID MATERIAL Filed Aug. 31, 1954 3 Sheets-Sheet 1 INVENTOR ATTORNEYS May 22, 1956- GARDNER 2,746,075

FILM APPLICATOR FOR LIQUID OR SEMI-LIQUID MATERIAL Filed Aug. 31, 1954 3 Sheets-Sheet 2 I N VENTOR PM h. 27mm ATTORNEYS May 22, 1956 GARDNER 2,746,075

FILM APPLICATOR FOR LIQUID OR SEMLLIQUID MATERIAL Filed Aug. 31, 1954 3 Sheets-Sheet 5 39 -wm 40 4a 38 38; 42

7-\ l 373 /////%l jffi 39 \r IN VENTOR J me h. JWLMV ATTORNEYS United States Patent Oce 2,746,075 Patented May 22, 1956 FlLM APPLICAT OR FOR LIQUID'OR SEMI LIQUID MATERIAL Paul N. Gardner,.Washington, D. C.

ApplicationAugust 31, 1954, Serial Nor 453,209.

8 Claims. (Cl. 15-436.)

The present invention relates .to ahand operated device for spreading a filtn of controlledfihickness upon a flat surface. and is a continuation-in-partof my co-pending applicationSerial No. 362,715, filed June 19,1953, and now abandoned, which in turn is a continuation-in-part of my application Serial No. 338,661, filedFebruary 25, 1953, now abandoned. Such devices are particularly useful in layingdownsample films of plastic or semi-liquidmaterialsv such as paints, varnishes, lacquers or the like for various types of comparative tests and analyses such as thoserelatingto color, opacity, weatherproofness, etc.

The improved filmapplicator or spreader according to the present invention, and as to which several embodiments are hereinafter described and illustrated in the accompanying drawings, has many advantages over those constructions now on the market. Onev advantage is that it enables the film to bebetter established and drawndown from the starting, mass toits final thickness. This is achieved by an improved form of doctor blade featuring a leading surface portion arranged at an appreciable angle to the mass and surface onwhichthe film is to be spread, a comparatively long, intermediate surface portion arranged'either parallelwith or at a very slight'angle to said surface. whereby the film is gradually drawn down to the desired thickness, and a trailing surface portion arranged substantially parallel to and spaced from said surface and which works the film to a perfectly flat and final gate thickness.

It should be mentioned before going further that the expression gate thickness means the thickness of the material as it passes through the gate opening between the trailing surface portion of the doctor blade and the surface on which the film is spread. Actually the fihn after it has been deposited on the surface will show a final thickness of the order of one-half the height of the gate opening dependent upon the viscosity and levelling quality of the material being deposited. The film applicators are accordingly calibrated in terms of gate opening rather than final film thickness.

Another advantage attendant the improved construction is the accuracy with which it is calibrated. Also the doctor blade may be adjusted to different gate opening positions to lay down films of different and most accurately ascertained gate thickness.

In accordance with the invention the film spreading device is comprised generally of an elongated body member having side rails extending longitudinally and defining therebetween a longitudinally extending channel in which is arranged a doctor blade for drawing down a mass of the plastic material into a film of the desired thickness. The channel is inclined slightly with respect to the plane of film application and the blade can be adjusted to different positions along the channel. to make corresponding adjustments in gate opening and hence film thickness.

In theaccompanying drawings which illustrate preferred embodiments of the invention,

Fig; 1. is a perspective view: of one; embodiment of-the device asseen from itstop side;

Fig. 2 is also a perspectiveviewof the, device as seen with its bottom side up;-

Fig. 3 is a central, longitudinal verticalsection through Fig. ldrawn to an enlarged scale;

Fig. 4 is a fragmentary central longitudinal vertical section drawn to a scale even larger than-Fig. 3 tobetter show certain important details of construction;

Fig. 5 is a bottom perspective view similar to,Fig.,2 illustrating a slightly different embodiment particularly adapted to laying down very thin films;

Fig. 6 is acentral, longitudinal vertical section through Fig. 5;

Fig. 7 is a perspective'view of still another modification of the invention; and

Figs. 8 and 9 are sectional views taken on lines 8 -8 and 9-9 of Fig. 7, respectively.

With reference now to.Figs. lj-4. of the drawings, the film applicator is seen to be comprised-of a main rectangular block. 1 which can be made of thick, high density metallic barv stock such as copper, bronze or brass or the like in order to have considerable weight and thus minimize the possibility of its being lifted by the plastic mass from the surface on which it is slid while the film is being formed. This is important in cases where the plastic mass may be on the stiff; side and resistsdrawing down.

A rather, wide channel 2 is milled into the lower face of theblock 1-. This channel extends longitudinally from one end of the block to the other thereby establishing longitudinal railportions 3 atthe sides of the block. The lower faces fia of these rail portions are flat and co-planar andrit is these faces which serve to support the block upon the fiat surface on which the film is to be laid down.

The ceiling of the inverted channel 2 has a gradient with respectto the. plane, containing rail faces 3a and, as will becomeapparent at a later point in this description, it is this gradient that establishes the range of film thickness that can be laid down by the device. In the present embodimengthe gradient is .005 inchper inch of length of the channel but it Will-be understood that this particular gradient is merely exemplary.

Arranged toslide along and in contact with the face of channel 2.is the doctor blade 4 by which the mass of plastic material 5 is drawndown into ajilm of the desired thickness. The width of blade 4 is made substantially equal to the distance betweentheinside faces 3b of, rails 3 so as to provide a sliding fit which permits the blade to be adjusted longitudinally of channel 2. For locking the blade to block 1 at any selected position along the channel it will be seen that a slot 6 isprovided through block 1, the slot being located intermediate the sides of the block and extending parallel to the rail. portions 3. Projecting through slot 6 is a stud 7', the lower end of which is secured to blade 4 and the upper end of which, being above the upper face of block 1, is threaded to receive a locking nut 8 which overlaps the marginal portions of slot 6 and establishes a locking action for the blade when screwed downto engage suchportions. Also securedto blade 4' by screw action and projecting upwardly through slot-6 is an index pin 9 havingits upper end face arranged flush with the upper face of block 1 and provided with an index line 92! adapted to register with the graduations on scale 16' arranged along one edge of slot 6 As seen best in Figs. 3 and 4, the front or leading end 4a of doctor blade 4 is bevelled rearwardly in a downward direction at an appreciable angle, for example 45, to the horizontal plane containingrail faces 3a so as to engage and force themass 5 into its initial film stage. Bevelled. portion 4a is followed by a much longer, intermediate flat surface portion 4b arranged at the same angle; to thehorizontal? plane containing railv faces. 3:: as; is the. gradient ofr hanncl; 2., his for the reason; that surface 4b; p rallel: with: he p face-othe. blade that containing rail faces 3a in all positions except the position of zero thickness and the height of portion 40 from the plane containing rail faces 3a constitutes the height of the film gate which of course is directly related to the final film thickness of any material of a given viscosity and levelling quality.

As should now be evident, the desired gate-opening can be selectively increased by adjusting blade 4 along the slightly inclined channel 2 in a direction forward from the rear, position shown in Figs. 1 and 2, the effect of which is to cause the trailing, horizontal portion 40 of the blade to move parallel to itself away from the plane containing rail faces 3a. At the 0 position, portion 4c of the blade is of course flush with rail faces 3a.

Calibration of the illustrated embodiment where films corresponding to a gate opening down to zero height can be spread is also facilitated by its novel construction. In making up doctor blade 4, the taper existing on intermediate surface portion 412 is first carried through to the rear end of the blade. The blade is then assembled on block 1 and locked by nut 8 at the 0 position on scale 10. The trailing surface portion 4c of the blade which then will extend above the plane containing rail faces 3a is then ground down carefully until it is exactly flush with rail faces 3:: thereby establishing in a most accurate manner the zero gate opening position of the applicator.

The film applicator according to the present invention is also attractive because it provides a very long scale that makes possible a greater spacing between graduations and hence a more accurate and finer selection of gate openings and hence film thicknesses. As previously stated the gradient of channel 2 in the embodiment illustrated in Figs. l-4 is .005 inch per inch of length and the gate opening range is from 0 to 10 mils. Scale 10 therefore has major graduations of 1 mil and minor graduations of .5 mil. However other gradients can be adopted to establish different ranges of gate openings such as from 0-1 mil, 0-20 mils, 0-40 mils, etc.

Figsv 5 and 6 illustrate a slightly different embodiment adapted for the laying down of very thin films of comparatively large area corresponding to a gate opening of the order of 1 mil or less. It is possible that when the blade in the embodiment of Figs. 1-4 is set for very low gate openings of the order of 1 mil or less, the paint may build up a pressure as it is being drawn down to its final thick ness sufiicient to lift the blade notwithstanding the fact that the applicator is held down as firmly as possible with the hands, thus resulting in a film slightly thicker than that set on the film gate opening selector.

With reference now to Figs. 5 and 6 it will be seen that the applicator block 21 is of generally the same construction as that shown in Figs. 1-4 except that it is wider and is provided with three parallel spaced slots 26 for receiving three studs 27 secured to the blade 24. An index pin 29 on blade 24 projects upwardly through the center one of slots 26 and the upper end of pin 29 is provided with an index line adapted to register with the graduation of a scale arranged along one side of the center slot 26 in the same manner as shown in Fig. l.

The ceiling of channel 22 is also provided with a plurality of shallow recesses 22:: which extend parallel to the direction of movement of blade 24. These recesses serve to reduce the area of sliding frictional contact between the bottom face of channel 22 and the upper 4 face of blade 24 thus making it easier to adjust the blade along the channel and also serve to prevent the blade from sticking against the bottom of channel 22 after a film has been laid down upon a surface and the instrument is being disassembled for cleaning.

The principal difference between the two embodiments lies in the configuration of the blades. It will be noted that in the embodiment of Figs. l-4, the intermediate fiat surface portion 4b of the blade merges along a line into the short trailing surface portion 40 that always lies parallel to the horizontal plane containing rail faces 3a. In the embodiment of Figs. 5 and 6, the trailing surface portion 240 is also short as compared with the length of the blade and likewise always lies parallel with the rail faces 23a and is calibrated in the same manner. However the intermediate portion 24b of the blade, instead of merging with the trailing portion 240 along a line is actually offset from the latter by a shoulder 25. The effect of this change is to provide a larger space for the material under the intermediate portion 24b which allows the material to pass more freely underneath the blade without building up a pressure sufiicient to produce a lifting action on the applicator body as the latter is moved across the surface on which the film is being deposited. The leading edge portion 24a of the blade is at the same angle as blade portion 4a of the Fig. 14 embodiment.

In the embodiments of the invention so far described, the side rail portions of the applicator block are integral with the main body thereof. Figs. 7-9 illustrate a further modification wherein the side rails are made separately and then secured to the block. With reference now'to these views, the applicator is seen to be comprised of block 32 which is made preferably of hard aluminum, the block having a pair of parallel spaced slots 33 for receiving respectively, an index pin 34 cooperative with scale 35 on the upper face of the block 32, and a stud 36, the upper end of which is threaded to receive the locking nut 37. Stud 36 and index pin 34 are secured to the blade 38 which is adjustable lengthwise of the block and slots 33 in the channel established by the underface of the block and inner faces of side rails 39, 40, these rails being made preferably from stainless steel, and being secured to the block 32 by means of Allen screws. As in the embodiment of Figs. 5 and 6, the ceiling of the channel in block 32 is provided with shallow recesses 42 to reduce surface friction between the channel and blade.

in the previously described embodiments of the invention the necessary slope between the path of the blade and the surface on which the film is deposited is established by a slight taper on the underface of the block, i. e. on the surface on which the blade slides, relative to the top face of the block and the rail faces which are parallel. In the embodiment shown in Figs. 7-9, the blade path slope is established by a taper on the lower faces of the side rails 39, 40, relative to the upper and lower faces of the block which are parallel. V

The applicator has a range of 0l0 mils, the gradient of the taper being 5 mils per inch, the same as in the Fig. 1 construction thus providing a relative large spacing between graduations and hence a most accurate and fine selection of film thickness.

The configuration of blade 38 is similar to that shown in the embodiment of Figs. 5 and 6 except that the leading edge 38a is curved rather than bevelled. Moreover, as distinguished from the integral blade construction of Figs. 5 and 6, the trailing end of blade 38, which preferably is a plane surface parallel to the plane containing the lower faces of side rails 39, 40, is constituted by the lower face of a rod 38b of a rectangular cross section extending across the rear end of the blade and set into a correspondingly configured recess therein, the rod 38b being made preferably from stainless steel and the main body of the blade being made preferably from hard aluminum. As in the other embodiments the lower face of the insert 38b is co-planar with the lower faces of the side rails 39, 40 when the blade is adjusted to its 0 position on the scale 35.

None of the illustrated embodiments include a reservoir for the liquid or semi-liquid material to be applied but the material can be deposited in advance of the leading portion of the blade from a small syringe, the discharge end of which can be inserted in the slot 6 of the first described embodiment.

In conclusion it should be evident that I have provided an applicator that combines accuracy with simplicity in construction. There being only two main parts, the block and blade, cleaning and maintenance are reduced to a Moreover it is to be understood that the embodiments used to illustrate my invention are to be considered typical rather than limitative and hence various minor changes in the construction and arrangement of components may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A device for applying a film of material to a flat surface comprising a block having depending substantially parallel side rails adapted to rest upon the surface, said side rails defining therebetween a channel extending in the direction in which the block is moved to apply the film, the lower coplanar faces of said side rails being at a slight slope with respect to the ceiling of said channel, a doctor member seated in and movable along said channel, said doctor member including a working edge parallel with the plane containing the lower faces of said side rails, and means for securing said doctor member in different positions of adjustment along said channel thereby to effect corresponding changes in the distance between the working edge of said doctor member and the lower faces of said side rails.

2. A device for applying a film of material to a flat surface as defined in claim 1 wherein said side rails and block are integral.

3. A device for applying a film of material to a flat surface as defined in claim 1 wherein said side rails constitute separate elements secured to the bottom of said block.

4. A device for applying a film of material to a flat surface as defined in claim 1 wherein said side rails constitute separate elements secured to the bottom of said block, the lower face of said block constituting the ceil- 6 ing of said channel being parallel with the top face thereo and the lower faces of said side rails being at a slight slope with respect to the faces of said block.

5. A device for applying a film of material to a fiat surface as defined in claim 1 wherein the means for ad justing said doctor member to different positions along said channel is comprised of a slot'in said block extending parallel with the channel therein from the upper face of said block to the channel, a stud secured to said doctor member and extending upwardly through said slot, said stud being threaded at its upper end, and a locking nut threaded on said stud and adapted to be screwed down into contact with the marginal portions of said slot.

6. A device for applying a film of material to a flat surface as defined in claim 5 wherein said doctor member includes a second stud secured thereto and which extends upwardly through a slot in said block extending parallel with said channel, said second stud having index means thereon cooperable with graduations on a scale arranged longitudinally along said slot.

7. A device for applying a film of material to a flat surface as defined in claim 1 wherein said doctor member is constituted by a plate member seated in said channel and a which is slidable to different positions of adjustment along said channel in contact with the bottom face of the channel, said doctor member having a sloped leading end adapted to initially contact the material and force the same towards the under side of the doctormember as the block is slid upon the fiat surface, an intermediate plane surface portion following said leading end and a trailing end plane surface portion substantially parallel with the under face of said block.

8. A device for applying a film of material to a flat surface as defined in claim 7 wherein the trailing end surface portion of said doctor member is offset from the intermediate surface portion thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,993,055 Gerstenberg Mar. 5, 1935 2,151,183 Bradley et a1 Mar. 21, 1939 2,303,120 Greaves-Walker Nov. 24, 1942 2,436,351 Bradley Feb. 17, 1948 2,607,124 Dery' Aug. 19, 1952 2,664,583 Oishei Jan. 5, 1954 

